Honeycomb panels have been employed for many years because of their great strength and durability combined with light weight. Generally, honeycomb panels comprise a series of abutting hexagonal cells. The walls of the cells are typically a kraft paper, sometimes resin-impregnated for water resistance. Of course, other materials such as plastic films can also be employed if desired. As will be appreciated, the width of the cells, the height of the cells or the material can all be varied to impart desired characteristics to the honeycomb material.
Typically, face sheets cover the open ends of the cells. Such face sheets are also generally kraft paper though other materials such as plastic films, aluminum foil and the like have been employed.
It is often desirable to fold the honeycomb panel. For example, inserting three ninety degree bends which quarter a honeycomb panel will form the walls of a square box. By varying the location and number of such folds, other polygonally-shaped boxes may be produced. Further, intersecting folds combined with complete cuts of honeycomb panels can yield various corner and edge protectors.
The corners and edges of any product are the most likely to come into unwanted contact with other objects. Such contact can result in damage such as scratches, dents, chipped paint and the like. If severe enough, such damage can result in an unsalable product and resulting loss. Even minor damage results in a loss of aesthetics and often results in lowered prices.
As a consequence, many edge and corner protector products are available to manufacturers and shippers to guard against such losses. Some competitive products are manufactured of expanded foam, corrugated paper or even composite materials such as a corrugated corner protector with one or more honeycomb panels glued to it to provide additional protection. However, many edge and corner protector products use honeycomb panels to take advantage of its properties.
Specifically, honeycomb provides thicker protective material with higher strength while using less paper than a comparable corrugated panel. Further, paper honeycomb is a recyclable product as opposed to expanded foam.
To use honeycomb panels for edge and corner protection, the honeycomb panels must fold properly. There are three methods currently in use today to fold honeycomb panels: pressure scoring, slit scoring and V-cut scoring.
The pressure score is formed by pressing a cylinder into the honeycomb panel. The cylinder forms an arced depression in the panel which does not cut either of the two face sheets. If pressure scored from both sides, the resulting double scored honeycomb panel section will act as a two-way hinge.
However, such a pressure-scored honeycomb panel often does not fold predictably along the chosen line. In addition, the effort required to bend the honeycomb panel into the desired angle toward the depression is high. It should be understood that a high folding effort may be undesirable in some applications.
Lastly, two such pressure scores cannot be situated in close proximity to each other on the same side of the panel without special arrangements. Each pressure score competes for the face sheet which results in tearing of the face sheet if two pressure scores are proximate to one another. To overcome this obstacle, special spring movable wedge pairs have been employed that allow the proximate wedges to move towards each other to relieve the face sheet stress. However, the resulting scored panel will actually be shorter than the unscored panel by the distance so moved.
Another common method of folding honeycomb panels is a slit score. A knife or razor simply slits the honeycomb panel completely through one face sheet and the honeycomb core, leaving only the second face sheet intact to act as the hinge. The panel is then folded away from the slit. This method is quick, accurate and results in a very low folding effort. The slit score lends itself to long-length slitting for edge protection or interior reinforcement of long packages. In addition, die-cut slit scoring can produce elaborately configured corner protectors.
However, the slit score does not protect well in direct corner impacts. Only the second face sheet covers an exposed edge or corner and thus the corner impact strength is low. In addition, the exposed honeycomb core often detracts from package aesthetics.
The last method is the V-cut score. A V-shaped trough is sawn completely through one face sheet and the honeycomb core. The vertex of the "V" is just above the second face sheet. By folding the "V" cut closed, the honeycomb panel will form a clean looking corner having an angle dependent upon the angle of the V-cut.
However, this method is limited by the complexity of the equipment needed to saw a number of V-shaped troughs in parallel. In addition, such cuts cannot be performed via a die-cut process, so products with intersecting fold lines such as corner protectors have not been produced using this method.
What is needed is a process for producing folds in a honeycomb panel which has the ease and simplicity of slit scoring yet produces the aesthetics of V-cut scoring. The method should also be usable in a die cut process as well as a continuous process so that polygonal containers, edge protectors and corner protectors are easily manufactured. The resultant honeycomb panel should fold predictably and should have a low folding effort with good corner impact strength.
The present invention meets these desires.